Control of the optical wavelength division multiplexing (WDM) optical fiber transmission technology is an important factor in meeting the growing bit rate requirements in information transmission. Wavelength division multiplexing, hereinafter called WDM, consists in combining, on one and the same fiber, a plurality of modulated signals each carried by a channel with different wavelength. Thus, the overall bit rate of a transmission line is equal to the sum of the bit rates of the different signals. However, WDM demands accurate control of the wavelengths used, both in transmission and in reception. Transmission over a badly controlled wavelength channel can in fact create interference with another signal present on the line, and therefore cause degradation to both signals, also called spectral collision. The reception of a signal over a channel with badly controlled wavelength by a receiver can cause the quality of the reception to be reduced or a signal other than that which was actually intended for the receiver to be detected. Optical transmitters and receivers that have a fixed or tunable operating wavelength can be used in WDM networks.